Completed experiment

Cardarine (GW501516)

No detectable benefit, unresolved long-term safety questions, and no reason to continue. This experiment is closed. Personal experiment record, not medical advice, prescribing, sourcing guidance, or an instruction to copy.

Outcome: I did not find a qualitative signal strong enough to keep using Cardarine. Given the missing long-term human safety data and the historical rodent cancer signal, no clear personal benefit means no reason to continue. Filed as no signal.

Research Summary

What it is

Cardarine (GW501516) is a PPAR-delta agonist developed by GlaxoSmithKline and Ligand in the 1990s and 2000s. It is commonly mislabeled as a SARM. It is not one. It does not act on the androgen receptor at all.

Mechanism

It activates PPAR-delta in muscle, which shifts fuel use toward fatty-acid oxidation and turns up genes tied to endurance and mitochondrial activity. In rodents it increased running endurance and pushed muscle toward more oxidative, fatigue-resistant fiber behavior, which is why it gets described as an exercise-mimetic.

Reported effects

The reported effects, mostly from preclinical work and human anecdote rather than controlled human trials, are improved endurance, fat loss, a favorable lipid shift toward lower triglycerides and higher HDL, and reduced inflammatory signaling.

Why development stopped

Long-term, high-dose rodent studies running close to two years showed cancer across multiple organs. Development was halted around 2007. It is banned in sport, and it carries a rare athlete-warning notice from anti-doping authorities.

Human safety data

There are essentially no long-term human trials. The dosing and duration in the rodent cancer studies were extreme relative to what people use, but that does not make the human risk known. It makes it uncharacterized, and that uncertainty is the central fact to hold onto.

The Experiment

Protocol

I started at 10 mg per day and moved to 20 mg per day after the first 15 days.

Hypothesis

The goal was qualitative: to see whether the endurance-and-fuel-use story that shows up in the research translated into anything I could actually feel and sustain during hard training, without leaning on stimulant-style effects.

Why I tested it

The draw is the mechanism. A lever that nudges the body toward using fat for fuel and supports oxidative, mitochondrial capacity sits right on the performance-and-longevity overlap I care about. I went in with eyes open about the cancer signal and the missing human data, decided the uncertainty was mine to carry, and chose to document the n=1 honestly rather than pretend the risk is not there.

Result

I did not detect a meaningful qualitative signal. No clear endurance change, no training-feel improvement, no recovery difference, and nothing that made the compound earn a continued place in the routine.

Decision

I am closing this as a no-signal experiment. With an optional compound that has no approved human-use path, no long-term human safety record, and a known preclinical cancer concern, the burden of proof is high. For me, Cardarine did not clear it.